Oral anatomy Flashcards
(35 cards)
What forms the first part of the respiratory tract?
The left and right nasal cavities
What is contained in the mucosa in the upper part of the nasal cavity?
Olfactory receptors
Where are olfactory receptors found?
In the mucosa in the upper part of the nasal cavity
What do the axons of olfactory receptors form?
- Olfactory nerves (CN1)
How are the left and right nasal cavities separated from
- Each other
- the oral cavity
- the brain
- They are separated from each other by a thin midline septum, formed of cartilage and bone (septum will only be seen on one half when the head is bisected)
- They are separated from the oral cavity by the hard palate
- They are separated from the brain superiorly by bone
What are 2 things the nasal cavity communicates with?
- The nasopharynx posteriorly
- The paranasal sinuses - cavities within the skull bones
How is the septum of the nasal cavities formed?
- It is formed of cartilage anteriorly and two thin plates of bone posteriorly
- The perpendicular plate of ethmoid bone forms the superior part of the posterior septum.
- The vomer forms the inferior part of the posterior septum.
How many projections of bone are there in the lateral all of the nasal cavity and what are they?
- There are 3 projections of bone. The superior, middle and inferior conchae/turbinates
What are the spaces inferior to the turbinates called? And what happens as inspired air passes through them?
- Meatuses (singular meatus)
- As air passes through them, it is warmed, humidified and filtered
What is the cribiform plate and what is its function?
- The cribiform plate (a portion of the ethmoid bone) separates the nasal cavity from the cranium and the brain
- It is a delicate section of bone that is perforated with tiny holes.
- The axons of olfactory neurons pass through the perforations to form the olfactory nerves which travel to the brain.
Where are the olfactory nerves located?
- They are located in the spheno-ethmoidal recess in the upper nasal cavity, between the superior concha and cribiform plate.
How many paranasal sinuses are there and where do they lie?
4.
- Frontal sinuses- lie within the anterior part of the frontal bone (it lies over the orbit and across the superciliary arch aka eyebrow)
- Ethmoid air cells- lies within the ethmoid bone (located in between the eyes, superior to the nasal cavity and medial to the orbits)
- Sphenoid sinuses lie within the sphenoid bone (just posterior to the ethmoid sinus and inferior to the pituitary gland)
- Maxillary sinuses lie within the maxilla of the facial skeleton (roof is the floor of the orbit and the floor is the alveolar process- structure holding the roots of our teeth in place)
Where do the 4 paranasal sinuses drain via small ducts?
- Frontal sinus drains into middle meatus
- Spehnoid sinus drains into spheno-ethmoidal recess
- Ethmoid air cells drain into the superior and middle meatuses
- The maxillary sinus drains into the middle meatus
What is the nasolacrimal duct?
Why do we have running nose when we cry?
- The nasolacrimal duct (which is received by the nasal cavity) drains the fluid that lubricates the anterior surface of the eye (tears).
- The duct opens into the inferior meatus
- When we cry, we get a runny nose as excess fluid runs down the nasolacrimal duct
The nasal cavity communicates with the middle ear. What is the middle ear?
- A small cavity within the temporal bone that is modified for hearing (it has 3 tiny bones which transmit sound waves to the inner ear)
What is the auditory tube?
Where can its opening be seen?
What is its function?
- The auditory tube connects the nasopharynx to the middle ear
- Its opening can be seen on the lateral wall of the nasopharynx, surrounded by a slight bulge formed of tonsillar tissue
- The auditory tube allows air to pass into the middle ear, so that pressure on either side of the tympanic membrane (ear drum- located between the middle and external ear) is equal
- This equal pressure is important for optimal conduction of soundwaves.
What is the nasal cavity supplied and innervated by?
- It is supplied by several arteries including branches of the maxillary artery- terminal branch of the external carotid artery.
- An anastomotic network formed supplies the nasal septum (which is often the site of bleeding in a nose bleed- epistaxis)
- The sensory innervation of the nose is via branches of the trigeminal nerve (CN V)
What is the function of the palate and what is it made up of?
- The palate separates the nasal cavities from the oral cavity
- It is composed anteriorly of bone - the hard palate
- It is composed posteriorly of muscle - the soft palate
- The palate forms the roof of the oral cavity
What is the hard palate formed by and what is its function?
- The hard palate is composed of 2 bones.
+ The palatine bone of the maxilla
+ The horizontal plate of the palatine bone
Its function include
- Preventing food or fluid from entering the nasal cavity
- We push our food agains the hard palate during the first phase of swallowing, forcing food and fluid into the oropharynx
- We push our tongue against the hard palate to articulate certain sounds
What would happen when someone’s palate does not form properly during embryological development?
- This is called a cleft palate
- It would result in difficulty eating, swallowing and with speech if not repaired
Where is the uvula found?
The uvula hangs on the posterior border of the soft palate which lies posterior to the hard palate.
What happens to the soft palate during swallowing?
- The soft palate is composed of several muscles which contract during swallowing, elevating the soft palate.
- Elevation of the soft palate closes off the nasopharynx from the oral cavity, preventing reflux of food and fluid into the nasal cavity.
What are muscles of the soft palate innervated by?
- The vagus nerve
What are the boundaries of the oral cavity?
- Superiorly by the hard and soft palate
- Inferiorly by soft tissues and muscles
- Laterally by the cheeks (containing buccinator muscles, used in swallowing, blowing and sucking)
